Fluid gasification apparatus

ABSTRACT

Apparatus for gasifying a liquid with a fluid supplied in liquid form has a discharge conduit for the fluid in which there are one or more restricted cross-section flow paths in a material providing a heat source for converting the fluid to a dry gas. Sealing means are urged resiliently against the open lip of a liquid-filled container into which the discharge conduit projects. Control means for the discharge rate of the dry gas flow from the conduit limit the pressure rise in the container. The sealing means comprises portions of greater flexural compliance permitting excess pressure to be vented from the container. The apparatus may comprise two telescopically movable parts, one holding the liquid container and the other holding a sealed bulb of the gasifying fluid. Said container and bulb are mounted in the parts such that said telescoping movement adjusts itself to accommodate different sizes of container and capsule.

FIELD OF THE INVENTION

This invention relates to apparatus for transforming a fluid in the formof a liquid or a wet vapour (that is to say a fluid which is wholly orpartially in its liquid phase) into a dry gas (that is to say a fluidwhich is wholly in its gaseous phase). More particularly it is concernedwith apparatus for charging liquids (the term "liquids" being hereintended to include also emulsions and suspensions) with pressurised gasso transformed. In one of its aspects the invention is concerned withthe use of encapsulated liquid gas products that are to be dischargedinto a liquid container to gasify the liquid therein.

BACKGROUND OF THE INVENTION

There are many processes that require the use of a fluid that is a gasat normal temperature and pressure but, for ease of handling and storageprior to use, is supplied in liquified form to be gasified whenrequired. One example is shown in UK Pat. No. 1,289,551, which describesa method of storing natural gas as a liquid by pressurising and coolingit, the user pipeline being supplied with the gasified product obtainedby expansion of the stored liquid. The supply is continuously maintainedand is stabilised in accordance with the user demand by allowing theliquid to be vaporised in a heat exchanger. Specifically, the heatexchanger employs a medium that undergoes a phase change at atemperature between the boiling points of the liquified gas at theminimum and maximum supply rates of the gas through the pipeline.

In another known apparatus described in UK Pat. No. 1,281,613 liquidnitrogen is used to provide a heated pressurised gas for fluid powerpurposes by being vaporised in a heat exchanger containing heatedalumina pellets as the heat exchange medium through which the nitrogenpercolates.

The fluids in these two examples cannot be liquified at normal (i.e.ambient) temperatures, and must be considerably cooled also. There aremany fluids that can be liquified by pressure without substantiallylowering their temperature below normal, and when the liquid issubsequently vaporised it is possible that the absorption of energy thatoccurs will result in cooling of the fluid sufficient to transform someof the fluid directly into the solid phase. The unwanted change to thesolid phase is undesirable as it can considerably delay the rate atwhich a quantity of the fluid is vaporised. This possibility exists forcarbon dioxide, as one example of a commonly used gas, and similarlynitrous oxide.

One use of pressurised gas, and in particular carbon dioxide, is for thegasification of liquids for consumption. Apparatus is known in which anintegral chamber in the apparatus is filled with liquid and a sealedbulb or capsule of liquid carbon dioxide is inserted and pierced toprovide the discrete quantity of fluid required to gasify the liquid.The fluid is discharged directly from the bulb into the top of thecontainer above the liquid surface so that it vaporises withoutdifficulty, but the process is extremely inconvenient because the liquidmust then be agitated under pressure to accelerate its gasification. Inaddition, this known apparatus operates as a syphon using the gaspressure to eject the gasified liquid, so that a substantial part of thegas charge remains in the container and cannot be used. The apparatushas a further major disadvantage that the chamber must be fullydischarged of liquid before a further quantity of liquid can begasified, so that its usefulness is limited.

Other apparatus is known from UK Pat. No. 1,453,363 in which the liquidin a removable container is gasified. It is therefore possible toproduce larger quantities of gasified liquid over a period of time, butthe apparatus is capable of operating only with one particular size andform of container to which it is adapted. Moreover this apparatus relieson the use of a large pressurised cylinder and gas is drawn off from thetop of the cylinder to provide the gasifying medium that is dischargedthrough the liquid to gasify it quickly. This apparatus is necessarilyrather complex and because it requires a large capacity cylinder of thegasifying medium it is inherently more dangerous in the event ofaccident or misuse. Because of the large amount of pressurised gasprovided by the cylinder contents the size of the container of liquid tobe gasified is restricted to limit the effects of its possible ruptureat the pressures that might be attained in this apparatus.

It is an important factor in all apparatus in which high gas pressurescan be generated, such as for producing gasified drinks, particularlyapparatus intended for general use and in situations where there may belittle or no preventive maintenance, that the apparatus is safe tooperate having regard to the maximum gas pressures that may begenerated. It is therefore customary to provide some form of pressurerelief valve, but that may not be sufficient in itself because over anextended period the valve may become defective without it necessarilybecoming apparent to the user.

In UK Pat. No. 1,453,363 mentioned above, there is a cam-operatedpressure relief mechanism that is operated and freed every time the lipof a bottle of liquid to be aerated is brought into sealing engagementwith the pressure gas supply means, so that it is ensured that themechanism is still operative before pressure is applied and the pressurerelief valve will be released if it has previously become stuck througha long period of non-use. This system requires a relatively complexmechanism that is expensive to produce, and moreover, although itensures the valve mechanism operates, it cannot ensure that pressurerelief gas path is not blocked. There may well be solid or gummyresidues left in the fluid flow passages of the apparatus from previoususe, and if these were to impede or block the escaping gas there stillcould be a dangerous over-pressure built up even though the valvemechanism itself operates perfectly.

SUMMARY OF THE INVENTION

One subject of the present invention is to provide an apparatus in whicha flow of gas is produced from the liquid state of a substance that canbe liquified by pressure and without substantially lowering itstemperature below normal, said flow being produced withoutsolidification of the fluid due to the cooling effect of its expansionfrom the liquid state.

Another object of the invention is to provide an apparatus for gasifyinga liquid in which the rate of discharge of the gas to the liquid iscontrolled in dependence upon the rate at which it is dissolved into theliquid.

A further object of the invention is to provide an apparatus forgasifying a liquid in a container wherein means are provided forpermitting replaceable containers of a range of different sizes to beemployed.

Yet another object of the invention is to provide an apparatus forgasifying a liquid in a container by employing a presealed capsule orbulb (the term "bulb" being used in this specification to include sealedcontainers of any shape for encapsulating pressurised fluids) of thegasification fluid and which permits a range of different sizes of bulbto be used.

In a still further object of the invention, there is provided apparatusfor gasifying a liquid in a container in which pressure relief means areprovided to limit the maximum pressure in the container while the gas isbeing discharged into it.

According to one aspect of the invention, there is provided apparatusfor gasifying a liquid in a container with a discrete amount of fluidthat is supplied in a liquified state, comprising a discharge conduitfor the passage of the fluid into a liquid-filled container that issealed from the exterior while said conduit is in connection therewith,there being one or more flow paths of extended surface area within theconduit, the said path or paths being formed in a material providing aheat source for said fluid whereby the fluid is caused to flow inintimate contact with the material forming said surfaces for heatexchange with said material to absorb therefrom the heat required toconvert the fluid to a dry gaseous state. (The term "extended surfacearea" means that the confining surfaces for the fluid flow aresubstantially larger in area than a direct throughflow connection ofcircular cross-section between the fluid supply source and theliquid-filled container. As will be described in more detail below, theterm "extended surface area" includes configurations in which a conduithas within its outer envelope integral or non-integral solid elementsaround which the fluid flows, and narrow bore conduit configurations inconvoluted form or in series and/or parallel connection.)

Because only a discrete quantity of wet fluid requires to be convertedat a time, in accordance with the volume of liquid in the container, andbecause of the extended surface area, the material mass forming thecontact surfaces can be arranged to have sufficient thermal capacity toyield the greater part of the heat required as the fluid flows throughthe conduit, without this material having to extract any significantamount of heat from its surroundings during the conversion of thepressurised wet fluid to its dry gaseous state. In performing itsfunction, the material yielding the heat is of course cooled, and if itstemperature falls below that of surroundings it will recuperate heattherefrom. This can begin before the whole of the discrete quantity ofwet fluid has attained the dry gaseous state, but normally most of theheat of recuperation will be absorbed in the relatively short minimumintervals between the gasification of successive quantities of liquid.

A compact arrangement can be easily produced by providing a multiplicityof small cross-section paths to obtain said extended surface area. Themultiplicity of paths within the conduit may be formed by the provisionof dividing walls that give a series of discrete smaller cross-sectionpassages; these passages may be connected in series or in parallel or ina mixed series/parallel configuration. In a preferred arrangement,however, a permeable mass is provided in one or more passages, so thatin the or each said passage the interstices of the mass provides a verylarge number of very small cross-section flow paths that are randomlyinterconnected for the fluid percolating through the mass and that havea correspondingly large surface area exposed to the fluid. The permeablemass may conveniently be composed of particulate material and/ormaterial in wire or strip form.

The material of said conduit interior surfaces may be arranged torecuperate heat simply by conduction from the surroundings, or means maybe provided to heat it electrically, e.g. by passing a current throughthe material to heat it by virtue of its electrical resistance, or byelectromagnetically inducing eddy or secondary currents in the material,or by incorporating an electrical heating element in the material butelectrically insulated therefrom.

The discrete quantities of the wet fluid may be supplied under pressureby a metering pump, or if the vapour pressure of said fluid at ambienttemperature exceeds the pressure required at the conduit outlet, afterallowing for the pressure drop in percolating through the permeablemass, by use of a capsule or bulb containing the discrete quantity ofthe fluid in the liquid phase.

The material of the conduit interior surfaces should be selected fromamong those chemically inert to the fluid being processed and shouldhave a high thermal conductivity to assist rapid heat recovery.

Depending upon the particular application of the apparatus, theconfiguration of the material providing these surfaces may bedifferently selected. If a permeable mass is used, for close control ofthe thickness or cross-sectional size of the elements forming theheat-transfer surfaces, material in wire or strip form may be mostsuitable, conveniently in bunched, matted or flocculent configuration.It may alternatively be in particulate form, perferably globularparticles with a controlled range of diameters.

When employing a permeable mass, an increase in the volume ofinterstitial space within the envelope volume of the mass relative tothe net volume of the constituent material will reduce the percolationpressure drop of the fluid but will also reduce the rate of heattransfer and would lengthen the time of recuperation of heat.

The resistance to the flow that is offered by the small cross-sectionpaths may be arranged to be sufficient to control the rate of flowthrough the conduit but this is preferably supplemented by further flowrestriction means.

Where any part of the whole of the permeable mass comprises metalparticles or metal wire the time required for recuperation can beappreciably reduced by sintering, which induces some continuity betweenadjoining regions of the mass and therefore enhances the heat flowthrough the material which is essential for heat recuperation. Ifrecuperation is to be achieved by taking heat from the surroundings itis preferable to sinter the permeable mass to the conduit walls toobtain intimate contact therebetween.

It may be preferred to provide non-return valves at the inlet and/or theoutlet of the conduit. At the inlet the valve will have a minimalloading bias so that it opens easily to admit fluid to the conduit, butat the outlet the larger biasing force will generally be required. Withboth ends of the conduit closed it is possible to avoid seepage from theinterstitial volume when the apparatus is not in operation between thetreatment of two successive quantities of fluid, e.g. if the fluid istoxic or expensive, or if it is important to avoid contamination of theinterstitial volume from the exterior.

In one particular use of the invention, liquified fluid in a presealedbulb is used to gasify liquid in a container, and by employing a heatexchange conduit as aforesaid it is possible to vaporise the fluid to adry gas very quickly. A particularly compact arrangement can be achievedif the heat exchange conduit is arranged to project into the containerthrough a top opening, but this is not necessary. In either case theconduit preferably has an outlet portion projecting below the liquidsurface in the container with a restricted outlet to break the gasstream into small bubbles that are quickly dissolved in the liquid.

According to another aspect of the invention, there is providedapparatus for charging a liquid with a gas, in which a valve device forcontrolling the flow of gas under pressure comprises a closure bodyhaving peripheral sealing means engaging with the walls of a chamber inwhich it is displaceable, the closure body being resiliently biasedagainst a gas inlet port having a cross-section less than the chambercross-section at said sealing means, whereby after the valve body hasbeen displaced from the inlet port by the gas pressure acting againstthe resilient bias an increased gas pressure force is applied to thebody to maintain the inlet port open, said displacement of the bodyplacing the inlet port in communication with an outlet orifice having arestricted cross-section limiting the rate of gas flow through thedevice.

Such gas flow control means can be employed at the outlet of a dischargeconduit of the form described above, or in other forms of gasificationapparatus, to control the rate of discharge of gas into the liquid independence upon the rate at which the gas is absorbed or dissolved intothe liquid.

According to a further aspect of the invention, there is providedapparatus for discharging a fluid from a sealed bulb into a liquid in acontainer, comprising mounting means arranged to permit relativemovement of the bulb towards the container, an opening device disposedbetween the bulb and the container opening the bulb during said relativemovement to permit the fluid to flow in a pressurised gaseous state intothe container, said opening device being provided with sealing means forengaging an entry opening of the container through which said gas isadmitted, the fluid pressure in the container acting upon the sealingmeans against said biasing means whereby the sealing means aredisplaceable away from said entry opening by an increase of thecontainer pressure over a limiting value to vent excess pressure fluidfrom the container.

Such apparatus may further comprise a safety blowout valve arranged toopen at a container pressure higher than said limiting value, in theevent of said displacement of the sealing means being prevented.

In a preferred form of apparatus according to the invention fordischarging gas under pressure into a liquid in a container through anopening in the container, the apparatus comprises a gas throughflowmeans circumferentially surrounded by annular sealing means forengagement with the container opening, said sealing means comprises aflexible sealing member for sealing contact with the container openingand means for supporting the sealing member against said lip, thesealing means having a flexural compliance to the internal pressure inthe container that is non-uniform with respect to its circumferentialextent around the gas injection means, whereby the flexible member isdeformable at an angular portion or portions of said circumferentialextent to release excess gas pressure in the container while being heldagainst the opening elsewhere around said circumferential extent.

With this arrangement, high pressure gas in the container can be venteddirectly into the surroundings without having to pass through lengthyconstricted passages that might be susceptible to blockage. Because therelief mechanism works without relying on sliding parts, but simplyrequires the flexure of a resilient sealing member, it is possible toprovide an arrangement which will always vent the container once thepressure rises above a predetermined level. Even if there isdeterioration of the material of the flexible sealing member over anextended period, this can be expected to increase the compliance of saidangular portion or portions so that the apparatus will simply vent at alower pressure and in all events a dangerous overpressure cannot buildup.

The variable compliance of the sealing means can be obtained by reducingthe thickness of the flexible sealing member over a portion or portionsof its extent engaging with the container opening, or by providing abacking member with a contoured or stepped supporting surface for theflexible sealing member whereby a similar portion or portions of theflexible member will flex first because of the lack of support from thebacking member there, or by a combination of both these features.

Preferably, the apparatus is arranged so that it is not sensitive to anyeccentricity between the container opening and the annular sealingmeans, which might otherwise result in the pressure at which ventingoccurs varying according to the precise location of the container withrespect to the annular sealing means. This may be accomplished byextending said portion or portions radially of the sealing means. In apreferred arrangement there are at least two radially elongate portionsof greater compliance disposed substantially symmetrically about theaxis of the annular sealing means.

In apparatus for discharging fluid from a sealed bulb into a liquid in acontainer, comprising mounting means having relatively displaceableparts for receiving the bulb and the container for permitting relativemovement therebetween in order that an opening device can operate toopen the bulb (e.g. for a hollow needle to pierce the bulb wall),according to another aspect of the invention there are co-operatingtoothed elements on said relatively displaceable parts occupying spacedperipheral portions on each part so that the two parts can be telescopedtogether with the toothed portions on each aligned with spaces betweenthe toothed portions on the other, said toothed portions being therebyengageable at selective different relative axial positions of the twoparts, whereby said engagement can be effected with the bulb-receivingpart in a predetermined position relative to the top openings ofcontainers of different heights.

Preferably that part of the mounting means that receives the bulb has asupport for the bulb that is displaceable in the telescoping direction,and to hold the bulb for it to be pierced there is an end stop limitingthe displacement of the bulb with said support when said parts of themounting means are telescoped together, whereby sad interengagement ofsaid parts is effected at relative axial positions of said partsdependent also upon the axial length of a bulb inserted in theapparatus.

In this manner it is possible to arrange the apparatus for use withdifferent sizes of bulb. It will be understood that such an arrangementmay be provided whether or not the mounting means are adapted to allowthe use of different height container openings, although it willgenerally be considered desirable to have both possibilities ofadaptability.

In a further aspect of the invention, in apparatus for releasing a fluidfrom a sealed bulb to charge a liquid in a container with a gasifiedfluid under pressure and comprising mounting means arranged to permitrelative movement of the bulb towards the container and a rupture devicedisposed between the bulb and the container arranged to pierce the bulbduring said relative movement to permit the fluid to flow into thecontainer, said mounting means includes a holder for the bulb andretaining means to support the bulb in said holder against the reactionto the gas pressure during said charging, said retaining means beingpivotally displaceable relative to the holder to and from anon-operative position in which it allows access to the holder forinsertion of a bulb therein, stop means determining a limiting operativeposition for the retaining means after the insertion of the bulb, thepivot attachment of the retaining means being offset from the line ofaction of the gas pressure whereby said pressure acts to urge theinserted bulb against the retaining means to hold it in said limitingoperative position.

Further details of the invention will be described by way of examplewith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical axial section of one form of apparatus according tothe invention,

FIGS. 2 and 3 are similar section views, to a larger scale, of theshuttle and of the outlet orifice valve respectively of the apparatus inFIG. 1,

FIG. 4 is a plan view from above of the lower casing part of theapparatus in FIG. 1,

FIGS. 5 to 9 are schematic illustrations of a modified form ofengagement between the upper and lower parts of the casing of theapparatus, FIG. 5 being a side view of one of the casing parts and FIG.6 a section on the line VI--IV of FIG. 5, FIG. 7 being a sectional partview of the lower of the two casing parts and FIGS. 8 and 9 being detailsectional views on the lines VIII--VIII and IX--IX in FIG. 7,

FIG. 10 is a composite illustration of a number of different forms ofheat transfer material in a heat exchange conduit for the vaporisationof a liquified gas,

FIGS. 10a, 10b and 10c illustrate some alternative cross-sectional formsof the heat exchange conduit,

FIGS. 11a, 11b and 11c are partial longitudinal sections showing heatexchange conduits provided with electrical heating means,

FIG. 12a is a cross-sectional view illustrating a form of conduit withextended internal surfaces,

FIGS. 12b and 12c are a detail axial section and cross-sectionrespectively illustrating ann alternative form of conduit,

FIGS. 13a and 13b are longitudinal and cross-sections or another form ofconduit,

FIGS. 14a and 14b are cross-sectional views showing a non-return valveat the inlet and outlet respectively of a heat exchange conduit,

FIG. 15 is a schematic part section of a modified form of the outletorifice valve of FIG. 3,

FIG. 16 is a composite view of two axial half sections illustratingportions of two further alternative forms of shuttle and bulb holder forthe apparatus of FIG. 1

FIG. 17 is a side view in half section, illustrating container sealingmeans for apparatus according to the invention,

FIGS. 18 and 19 are opposite end views, seen in the directions X and Yrespectively, of the sealing member of the sealing means in FIG. 17,

FIGS. 20 and 21 are end and axial sectional views of a flexible sealingmember for another sealing means for apparatus according to theinvention, and

FIGS. 22 and 23 are axial section and end views of a further form ofsealing means for apparatus according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring in particular to FIGS. 1 to 4 of the drawings, the apparatuscomprises an outer casing 2 which provides mounting means for a bottleor other container (not shown) containing a liquid to be carbonated anda carbon dioxide bulb B that itself may be of a conventional form usedto produce carbonated drinks domestically, e.g. holding a change of 8 gmliquid carbon dioxide. The bottle is mounted in a lower part 4 of thecasing and the bulb B in an upper part 6 that is detachably secured tothe lower part by a toothed or threaded arrangement to be described inmore detail below.

The container upper part 6 comprises a cylindrical lower skirt 8 and atop cap 10 abutting the skirt at a peripheral junction and securedthereto by snap ribs (not shown). The lower skirt has a top wall 12 witha flanged central aperture 14 in which a bulb holder 16 for the bulb Bis an interference fit, there also being engagement means (not shown)between the top wall and the holder to prevent relative rotation. Thetop cap 10 has an opening in its top wall that is closed by a pivotinglid 20 described in more detail below, attached to the bulb holder 16through an offset transverse pivot mounting 22. By swinging the lidclockwise from the position shown in FIG. 1, there is access to cup 24of the bulb holder for the bulb to be inserted, and the neck of the bulbbeing sealingly engaged by an O-ring 26 at the lower end of the cup.

The bulb holder 16 includes a downwardly open cylindrical portion 28 inwhich there is a sliding shuttle 30 that comprises a hollow needle 32projecting upwardly from it towards the bulb. The needle is biased awayfrom the bulb by a compression spring 34 acting between the shuttle andthe top wall 36 of the holder cylindrical portion. A stop ring 38 at thebottom of the cylindrical portion retains the shuttle within the holder.

The shuttle has a gas expansion tube 40 projecting downwards from it andterminating at an outlet orifice valve 42 near the bottom of the housinglower part to provide a heat transfer conduit for bulb fluid to flowinto the liquid. In use, the tube extends into the bottle of liquid,with the neck of the bottle sealed against a sealing disc 44 on theunderside of the shuttle, the upper and lower parts of the casing 2 thenbeing so positioned that the bottle forces the shuttle upwards, andtherefore the needle also, to pierce the bulb. The liquid carbon in thebulb vaporises as it passes through the expansion tube where the coolingeffect of the expansion is partly counteracted by heat transfer from thematerial of the tube, so that the formation of solid carbon dioxide isprevented and the fluid is introduced into the bottle as a dry gas tocarbonate the liquid there.

The upwards force of the needle, and the subsequent reaction to the gaspressure acting in the same direction tend to push the bulb B upwardsout of the holder cup 24, but this is resisted by the pivotable lid 20when, after a small movement to take up any clearance, the top of thebulb bears on the closed lid. Because of its offset pivot mounting 22,the lid will be urged anticlockwise (as seen in FIG. 1) but is preventedfrom moving any further in this direction when in the closed position byan end stop formed by a bottom edge 46 of the lid and an opposed topedge 48 on the top cap engaging therewith.

As can be seen in more detail in FIG. 2, the hollow needle 32communicates with a central passage 50 in the shuttle. The needle isfixed to the main body of the shuttle through its stem 52 provided withtwo O-rings 54 in series that act both to seal the bulb holder bore 56in which they slide and also to centralise the needle relative to thatbore. The central passage 50 in the shuttle connects the interior boreof the needle to a shuttle plug 62 wherein a transverse exit passage 64is closed by an elastomeric ring 66 that acts as a non-return valvepermitting fluid flow only from the shuttle into the gas expansion tube40.

The tube is filled with a permeable mass or matrix 68 of material actingas a heat source for evaporation and expansion of the carbon dioxide sothat it can be injected into the bottle as a pressurised dry gas flow.The material used for this purpose is required to be able to transmitthe necessary amount of heat very quickly to the carbon dioxide as itpasses through the tube, since the operation of the device with aconventional size of carbon dioxide bulb may occupy no more than two orthree seconds. It must also be able to recover heat from thesurroundings relatively fast, as the user may want to repeat theoperation every two or three minutes. Generally speaking, metallicmaterials will therefore be preferred for the permeable mass, and thematerial will in any event preferably be in the form of small particlesor filaments providing a multiplicity of small interstitial spaces thatform paths through which the fluid flows.

At the exit end of the expansion tube, the outlet orifice valve 42 hasthe function of preventing flow until a certain minimum gas pressure hasbeen established in the tube as the liquid carbon dioxide from the bulbevaporates. Referring to FIG. 3, the gas from the atomising tube reachesthe valve through a porous plug 74 that retains the heat yielding matrix68 in the tube and the gas pressure acts on a valve body 76 through anentry conduit 78 that is of smaller diameter than the valve body. Asealing disc 80 on the end face of the body confines the pressure to thesmaller area of the conduit cross-section as long as the valve body isheld against the entry conduit by a compression spring 82. Once the gaspressure overcomes the spring bias it acts on the full cross-sectionalarea of the valve body and the valve therefore snaps open as apredetermined opening pressure is attained. The flow past the valve bodythen occurs with a minimal pressure drop.

The rear of the valve body is sealed from the incoming gas pressure byan O-ring 84 and the gas can only escape into the bottle through anozzle orifice 86. This is of restricted cross-section so that thepressure drop across it is above the critical value and there is achoked sonic flow through the orifice. One effect is that the shearingaction of the relatively high speed gas flow emerging into the liquid inthe bottle breaks up the flow into very small bubbles that thereforedisolve more easily. Initially at least, the restricted orifice alsolimits the outflow rate of the gas and so maintains a requiredback-pressure in the atomiser tube 40.

As the gas pressure builds up in the bottle, it will also act on therear of the valve body by way of the opening 88 in the lower end of thevalve. The valve body is therefore sensitive to the pressure drop acrossthe orifice, and the spring 82 is so arranged that it will only allowthe valve to be opened when the resultant gas pressure on the fullcross-section of the valve body is above the orifice critical pressure.

As the gas pressure in the bottle builds up to its required final value,the rate of solution in the liquid closely approaches the rate of supplyof dry gas. Should there be any excess supply of gas, this is able toescape from the top of the bottle because the pressure acting on theshuttle sealing disc 44 at the upper lip of the bottle then causes theshuttle to move against the force of the spring 34, away from thebottle.

The apparatus is adapted to be used with bottles of a range of differentheights and diameters, e.g. with capacities of between 750 cc and 1100cc, with heights of between 250 mm and 320 mm and diameter up to 930 mm.The accommodation of different bottle heights is achieved by the form ofscrew thread engagement provided between the upper and lower parts ofthe casing. This comprises groups of teeth forming, on each part, tworack-like screw thread segments 92, 94. The upper part segments 92 areon the skirt 8 and extend over substantially the full height of theskirt, but the lower part segments 92 occupy only the topmost maximumdiameter region of the tapered casing lower part 4.

On each casing part, the two segments are diametrically opposed andsubtend an angle slightly less than the gap between segments on theother part. It is therefore possible to align the two casing parts sothat they can be telescoped axially into each other without engagingtheir screw thread segments. The teeth of the segments are obliquelyinclined to form a screw lead after said telescoping movement; as theyare interengaged by relative rotation between the casing parts 4, 6there will also be a further relative axial displacement between theparts.

In use, therefore, any bottle can be placed in the casing lower part 4that reaches the top of that casing part or projects somewhat above it,and the upper part 6 is lowered onto the lower part 4 while the twopairs of screw thread segments 92, 94 are kept out of alignment, the gasexpansion tube 40 being inserted into the container neck in thismovement. The casing upper part will come to rest on the bottle with thesealing disc 44 bearing on the top lip of the bottle, and when the upperpart is then rotated, the screw thread segments will engage and theupper part will be forced further downwards, firstly to engage thesealing disc firmly with the bottle lip and secondly to urge the shuttle30 upwards relative to the bulb holder 16 so that the hollow needle 32pushes the bulb against the closed lid 20 and is forced into the bulbinterior.

It will be noted that the bulb cannot be pierced and the contentsexpressed until the pivotable lid 20 is properly positioned to resistupwards movement of the bulb, i.e. with the edges 46, 48 abutting, andthe bottle lip is tightly engaged with the shuttle bottom sealing disc44.

As shown in FIG. 1, the smaller groups of teeth forming the segments 94of the casing lower part are engaged with the topmost portions of thelarger groups of teeth forming the segments 92 of the casing upper part,which is then substantially at its lowermost position on the casinglower part. It will be clear that if a taller bottle is used thatprojects above the top of the casing lower part, the apparatus will actin the same manner but the segments of the casing lower part will engagea lower region of the casing upper part segments, as determined by theposition at which the casing upper part comes to rest on the bottle lipat the end of the initial telescoping movement. It is to be understoodthat it is also possible to reverse the arrangement of segmentsillustrated, so that the smaller groups of teeth are on the casing upperpart and the larger groups on the lower part.

If different size containers are used, they may have differentdiameters, but they will be centered by a series of symmetricallyarranged resiliently flexible ribs 96 at the bottom of the casing lowerpart interior. These ribs starting from radial positions spaced from thecentre of the base, extend upwardly towards their outer ends at theperipheral wall 98 to which they are connected in web-like manner, andwill therefore tend to centre the bottle, in particular when a downwardspressure begins to be applied to the bottle by the screw engagement ofthe casing upper part.

As a further safety feature, should the shuttle 30 not move to ventexcess pressure in the bottle as the gas flows into it, a blow-out disc102 (FIG. 2) of elastomeric material is mounted on the piston 104 of theshuttle. This is positioned behind a small aperture 106 in the sealingdisc 44 that is located near the disc inner periphery to ensure it willopen into the top of the bottle inwardly of the top lip. Behind theblow-out disc 102 there is a larger aperture 108 in the piston 104 sothat the disc is supported only around a peripheral margin. At apredetermined pressure in the bottle, therefore, the flexible blow-outdisc will be deformed sufficiently for it to be driven through theaperture 108 and so leave an open passage for relief of the pressure inthe bottle.

To assist the initial location of the upper and lower casing parts oneach other, and to ensure that the full set of threads of the axiallyshorter groups of segments will always be engaged when the apparatus isbrought into use, it is possible to provide axial guide means betweenthe upper and lower casing parts as exemplified by FIGS. 5 to 9. Theguide means comprise a projecting rib 110 on that casing part 112carrying the smaller screw thread segments 94, and a thickened rim 114on the other casing part 116 preceding and circumferentially coincidentwith the larger screw thread segments 92 there, with a recess 118 inthat rim for the passage of the rib 110. The part 112 as illustratedcorresponds to the casing lower part 4 in FIG. 1, and the part 116corresponds to the upper part 6.

The rib is disposed between the segments 94 of its casing part. Itterminates with a tapered outer end extending to adjacent its casingpart rim, axially slightly beyond the segments 94, and its opposite endextends axially to the level of the inner end of those segments. The ribdoes not project radially beyond the root radius of the teeth of itsassociated segments. This means that when the two casing parts are beingassembled together, and the rib 110 has passed through the recess 118 inthe thickened rim 114 of the other casing part it can then move freelyover the screw thread segments of that other casing part.

When assembling the casing upper and lower parts together, therefore theuser first approximately locates the upper part on the lower part, andas they are brought together the tapered end of the rib 110 will providethe correct orientation between the parts as it engages the recess 118.While the rib is in the recess, relative rotational movement between thetwo casing parts is prevented, so that the screw thread segments cannotbe engaged until the rib has passed completely through the recess, andthe smaller groups of threads 94 have similarly passed through the gapsbetween the arcuate portions of the rim 114. At that stage the completeaxial length of the smaller segments will be engageable with thesegments of the other casing part. It is therefore ensured that the twocasing parts will be securely fastened together with a sufficient numberof segment teeth interengaged.

FIG. 10 illustrates a number of different forms of permeable mass ormatrix that can be used in the gas expansion tube 40, although notnecessarily all in the same tube. The figure shows a spiral of tightlyrolled wire gauze 120, a pile of wire gauze discs 121, or a mass ofparticles 122, or a random, flocculant mass of wire or thin strip 123 ineach case tightly fitting within the inside profile of the tubecross-section. Porous retainers 124 are fixed in the tube to hold thepermeable mass in place. The tube cross-section may take a variety offorms and FIGS. 10a, 10b and 10c illustrate some examples. The lattertwo examples can be assembled in honeycomb fashion to form a group ofsmall cross-section flow passages in series and/or parallel connection,with interposed sheet-like electric heating elements if desired.

FIG. 11a shows a modified expansion tube 40a with an inlet 126 to anannular space 127 containing the porous mass 68 into which a tubularenclosure 128 is inserted containing a tubular heating element 129.There is a communicating region below the bottom end of the enclosure128 between the inner and outer regions of the annular space and at thetop of the conduit an end space 130 communicates with a central exittube 131 to the outlet 132. Transverse porous retainers 124 are providedif the porous mass in loose powder form but may not be necessary if itis in the form of spirally wound wire gauze. The wet fluid entering at126 is constrained by the enclosure 128 to flow through the porous mass,first downwards through the outer region of the annular space 127 andthen upwards through its inner region, before exiting via the tube 131.The tubular electrical element is operated to transfer heat to theporous mass by conduction and may be energised continuously whilesuccessive charges of fluid are passed through the apparatus.

FIG. 11b shows another modified expansion tube 40b filled with theporous mass 68, retained if necessary by partition 124, and two metalcombs 134 at opposite ends of the conduit which penetrate longitudinallyinto the porous mass in electrical contact therewith to enable anelectric current to be passed directly through the mass, which is of anelectrically conductive material and which by virtue of the voidstherein has sufficient resistance to generate a heating effect withinthe mass. In this embodiment the material of the conduit 40b must be ofsufficient electrical resistance so as not to short-circuit the currentpath through the mass. Many suitable materials such as quartz orceramics are commercially available.

FIG. 11c shows an arrangement in which an electric inductance winding136 surrounds the tube 40c. In this embodiment the material of the tubeor conduit is chosen so as not to screen the porous mass and inhibit theinduction of eddy currents within the mass. To enhance the intensity ofthe eddy currents the porous mass is preferably sintered as describedabove.

FIG. 12a shows an example of the construction of an expansion tube orconduit 40d with a multiplicity of longitudinal inwardly projectingradial ribs 142 to form the extended internal surface area. These ribsmay extend to the centre of the conduit or there may be a significantcentral core space filled with porous mass 68, in this instance in wireform in any of the configurations already described. Instead of ribs, ananalogous extension of the conduit internal surfaces may be obtained ifthe conduit wall has a lobed configuration: this also results in anextended external surface area.

FIG. 12b shows an alternative construction of an expansion tube orconduit 40e with an internal helical fin 144 to increase the contactarea for the porous mass. For clarity only one helix is shown here andthat for only one half pitch of length, but of course multiple fins canbe provided at a desired pitch. Thus, FIG. 12c shows the finning as asix-start helix 144a. This latter figure also illustrates the packing ofthe interior of the tube with the porous mass, which fills the tube toits cylindrical wall although the fins are shown uncovered for clarity.

In the example illustrated in FIG. 13a there is a tube or conduit 40fwith a series of concentric tubes 146 in it, each with perforations 147around its walls adjacent opposite ends. At one end the annular spacesbetween alternate pairs of the tubes have porous end rings 148 tocontain the porous mass 68 that may fill all the annular spaces if extraheat exchange capacity is required. An end plate 149 closes the annularspaces off remote from the tube inlet end, so that in alternate annularspaces the fluid is constrained to flow downwards and in the interveningspaces it is constrained to flow upwards. As FIG. 13b shows, theconcentric tubes may be provided with ribs 150 the main purpose of whichis to enhance the transmission of recuperative heat from thesurroundings.

FIGS. 14a and 14b show examples of non-return valves 152 and 153 whichmay be incorporated respectively at the inlet 126 and at the outlet 132of the conduit. The inlet valve comprises an elastomeric sleeve 154 intension in an annular recess to cover a transverse hole 156communicating with the inlet 126, as in a so-called Woods valve commonlyused in pedal cycles, and is arranged to open at a very lowsuperpressure on its inlet side. The outlet valve comprises a ball 157urged onto a conical setting face 158 by a spring 159. Both valves areseparated from the porous mass 68 by the partitions 124 and both areshown with O-rings 160 to prevent leakage of the fluid.

FIG. 15 illustrates a modified form of outlet orifice valve 172, inwhich parts already described with reference to the orifice valve 42 inFIG. 1 are indicated by the same reference numbers. In this modifiedconstruction, a valve body 174 is moulded integrally with a diaphragm176 from a rubbery material. The diaphragm outer edge engages in arecess 178 in the inner wall of the valve housing, beyond the nozzleorifice 86, and the resilience of the diaphragm provides the biasingforce that holds the valve body on its seating. In other respects, thevalve operates in the same manner as the first-described example.

Further possible modifications of the apparatus already described areillustrated in FIG. 16. Although not shown, this apparatus also hasupper and lower casing parts engageable by screw thread segments in themanner described above, with the container for the liquid to be gasifiedbeing inserted in the lower casing part (not shown) and a conventional 8gm liquified carbon dioxide bulb B inserted in a bulb holder 200 in theupper casing part. However, the figure shows only the top wall 202 ofthe lower skirt of the upper casing part, on which lower skirt thesegments of the upper casing part are formed.

As has already been described, a hollow needle 204 is mounted in ashuttle 206 slidable in the bulb holder and urged downwards by a spring208. On the underface of the shuttle is resilient sealing disc 212 forengagement with the mouth of the container in the lower casing part, andengagement of the screw thread portions of the upper and lower casingparts is arranged to urge the container mouth into firm sealingengagement with the disc and to force the needle to pierce the bulb sothat gas under pressure can flow through the gas expansion tube into theliquid in the container.

In contrast to the first-described construction, however the shuttle nowcomprises, immediately below the needle, an enlarged cylindrical portionor barrel 214 that is slidable into a bore 216 of a spool, two differentforms of which are illustrated in the two halves of FIG. 16 andindicated by reference 218a and 218b. In both examples the spool has anintegral collar 210 below the barrel. The spring 208 acts on the spoolso that the shuttle and spool are urged apart, but the collar 210 limitsthis relative movement when it engages the underside of the barrel. Themovement of the spool is limited by a retaining clip 220 that projectsthrough the wall of the bulb holder into a cylindrical recess 222 in thespool, and FIG. 16 shows the spool and shuttle in their lowermostpositions.

In the example in the right-hand half of FIG. 16 there is an upper0-ring 224 mounted in the spool bore, to seal with the neck of the bulbB that has been inserted to rest upon a locating ring 225, and a lowerO-ring 226 is mounted on the barrel 214 to form a seal between thebarrel and the spool 218a when the shuttle is urged towards the bulb. Asmall hole 227 provides a vent for excess pressure from the spoolinterior between the O-rings when the barrel withdraws to a lowermostposition relative to the spool, at the end of a charging operation.

In the example in the left-hand of FIG. 16, the bulb is engaged by asealing sleeve 228 which both seals against the neck of the capsule andlimits its movement downwards into the bulb holder. The sealing sleeveis inserted into the spool 218b before a retaining ring 230 is appliedto secure the sleeve in place. As in the right-hand example, a lowerO-ring 216 is mounted on the barrel 214 to form a seal between thebarrel and the spool bore when the shuttle is urged towards the bulb. Avent hole is not required in this instance because gas can escape pastthe seal 228 when the axial sealing loading is relieved as the barrel iswithdrawn.

By making the effective seal diameter between the bulb and the seal, asprovided by the O-ring 224 or the sealing sleeve 228, either smallerthan or equal to the effective seal diameter between the spool and theneedle barrel, an increase of pressure in the space between the twoseals will not produce a resultant force tending to force the spooldownwards away from the bulb.

However, because the pressure load developed on the barrel istransmitted to the shuttle seal and increases the force with which theseal is applied to the container mouth, the barrel has a maximumpermissible diameter. Otherwise, the increase of the container reliefpressure, i.e. the pressure at which the shuttle is lifted to vent thecontainer interior, would become excessively high as the pressure in thespool bore increases. Therefore, the measures taken to ensure that theneck of the bulb remains sealed in the spool must also be effective withthe diameter of the barrel limited to the extent necessary to ensure thecontainer pressure will be relieved in safety.

In the result, it has been found possible to prevent separation of thebulb and the spool while at the same time restricting the load on theshuttle seal by limiting the barrel diameter if at the overpressureconditions to be expected in the spool bore, a limited resultantdownwards pressure force is allowed to develop on the spool that isalways less than the upwards force of the spring 208.

Both embodiments illustrated in FIG. 16 operate in a similar manner.Before the two casing parts are put together the liquified gas bulb isinserted in the bulb holder 200 in the upper casing part and aliquid-filled container is inserted into the lower casing part. Thespool 218a or 218b is in its lowermost position, with the upper shoulderof the cylindrical recess resting on the retaining clip 220, and shuttle206 is also in its lowermost position, depending from the spool collar210. The upper casing part has a pivoting lid of the form describedabove, mounted on the stub pivots 232 and this is closed once the bulbis inserted.

When the upper casing part is brought down onto the lower part thecontainer mouth engages the sealing disc to seal against it and in sodoing urges the shuttle upwards. Under its own weight the casing upperpart will move downwards while the bulb and spool remain in the samepositions relative to each other and the container, until the closed toplid comes into contact with the top of the bulb. In this position theaxial telescoping movement between the upper and lower casing parts iscompleted, and the casing top part is supported through the spring 208,with the needle still spaced from the bulb. If the screw thread portionsof the two parts are now engaged the bulb is brought down onto theneedle and the needle is forced into the bulb to release its contentsthrough the gas expansion tube into the liquid in the container.

Because the needle does not begin to pierce the bulb until the screwthread portions are partly engaged, it is possible to ensure that thetwo parts are securely interconnected before the apparatus begins to bepressurised. For example, if the screw thread portions are 90° segmentsit may be arranged that about one third of the full angular engagementof the thread portions is completed before the needle begins to piercethe bulb.

It will be clear from the foregoing description that because of therelative movement that takes place between the bulb and the pivoting lidit is possible to employ bulbs of a range of different lengths. Themaximum length is determined by the ability to close the pivoting lidwhen the bulb is first inserted and the minimum length is determined bythe permitted travel of the spool to reduce the distance between thepivoting lid and the bulb locating ring or sealing sleeve. For practicalpurposes in an apparatus intended for 8 gm carbon dioxide bulbs a spoolmovement of some 6 mm may be sufficient. This is in addition to theability to accommodate containers varying in height over a range of some10 cm.

Until the pivoting lid has been closed, the screw thread portionsbetween the casing part cannot apply the force required to pierce thebulb. Moreover, the lid cannot be closed after the upper casing part hasbeen lowered onto the lower casing part because with the lid open atthat stage the bulb will have been pushed to a position in which itblocks closure of the lid.

The risks of accidents from such misuse of the apparatus are thusavoided.

Referring now to FIGS. 17 to 19, a preferred form of pressure reliefmeans for apparatus otherwise of the form already described comprisessealing means having a planar annular sealing member 302 of siliconerubber or food quality natural rubber mounted on a rigid backing member304 that forms a cast or moulded shuttle providing gas throughflowmeans. Other features of the apparatus are not shown, but as in thepreviously described embodiments it comprises a casing in which theshuttle is axially slidable in the directions X,Y and is urged in thedirection Y by a spring against the open lip of the bottle which ismounted substantially coaxially with the shuttle in the casing, the lipthereby being held in sealing engagement with the end face 302a of theflexible sealing member. In FIG. 17 a screw-threaded section 305 isshown to which the gas expansion tube 40 is secured, and the apparatusalso comprises unillustrated means by which, as the sealing engagementis made, a carbon dioxide bulb or capsule is pierced and its contentsflow through the central axial passage 306 in the shuttle member to anoutlet nozzle 308 where there is a nonreturn valve 310 and to thebottle, which has previously been filled with water. As in thefirst-described embodiment, the non-return valve leads to a heattransfer conduit (not shown) where the bulb fluid is expanded to a drygas as it flows into the bottle.

The supporting surface 314 of the shuttle providing the backing memberfor the sealing member and through which the sealing pressure betweenthe flexible member and the bottle lip is transmitted, has two oppositeradially elongate recesses or slots 316. At these two positions,therefore, the flexible member is unsupported and can move away from thebottle lip. During the gascharging process, the bottle internal pressurecan rise considerably before the gas dissolves in the liquid, and thesealing member will flex at the unsupported portions when the bottleinternal pressure passes above some predetermined value, since the slotsare themselves open to ambient air pressure. Gas will then be ventedfrom the bottle until the pressure has dropped sufficiently to allow theflexible member to return into full sealing engagement with the bottlelip. By suitable choice of the dimensions and material of the flexiblemember, and of the dimensions of the slots, the flexural compliance ofthe unsupported portions in front of the slots 16 can be controlled toset the required safety blow-off pressure.

The gas escapes into free space as soon as it passes the bottle lip, andthe seal againt the lip is made afresh in each charging operation, ofcourse. There is therefore no risk that an accumulation of foreignmatter from previous use will prevent operation of the pressure relief.If the material of the flexible member should be damaged or deterioratewith the passage of time, this will simply result in the unsupportedregions flexing at a lower pressure, so that the arrangement has afail-safe characteristic in this respect.

It will also be seen that the blow-off pressure is independent of theforce with which the sealing means is held against the bottle lip, sincethe sealing member is still held in the same position against the bottlelip while its unsupported portions are flexed by the gas pressure. Nocomplex and sensitive mechanism is required, therefore, and duringnormal operation it is always possible to provide a secure seal for thecharging process.

FIGS. 20 and 21 show an alternative flexible sealing member 322 that canbe employed with a backing member 324 having a planar supporting surface326, in an arrangement otherwise similar to that in FIGS. 17 to 19.Through the backing member and the flexible member there is a centralaxial passage 328 for the injection of gas into the bottle through anon-return valve and a heat exchange conduit as already described, thisnot being illustrated in any detail. A planar face 330 of the flexiblemember faces the sealing face of the bottle lip, but at its rear facethe member has four equispaced radial recesses 332 which result in therebeing corresponding thin-walled unsupported portions 334 at the frontface. As in the first-described example, the unsupported portions areflexurally compliant and can be proportioned so as to allow gas toescape once a certain pressure has been exceeded.

FIG. 21 also illustrates how, even with the bottle lip L eccentric tothe sealing means, the pressure relief function of the sealing means isequally effective. It will be apparent from this that the flexuralcompliance of the reduced thickness portions to the bottle internal gaspressure is dependent on the circumferential extent of those portionsbut not on the radial position of contact of the bottle lip. It will beunderstood that a similar effect can be obtained using a single radialrecess or slot, although it is preferred to provide two or moreangularly spaced recesses or slots as this caters for a greater range ofeccentricity within given overall dimensions.

In FIGS. 22 and 23 an embodiment of the invention is illustrated similarto the preceding example but in which a planar flexible member 342 issupported by a backing face 344 on a shuttle 346 in which the radialrecesses or slots are replaced by an equispaced series of shorterrecesses or slots 348 arranged on a pitch circle concentric with theshuttle axis and corresponding to the bottle lip diameter. The areas ofthe flexible member overlying these slots thus form portions of greaterflexural compliance than the remainder of the member. If the bottle lipis located eccentrically on the flexible member, at the oppositediametrical regions of maximum eccentricity the slots will be entirelyoutside or inside the area encircled by the bottle lip and so not beoperative for the relief of the internal bottle pressure, but there is asufficient number of slots to ensure that one or more of them willsubstantially coincide radially with the bottle lip L, whatever itseccentricity, and so provide the pressure relief function. Therefore, itis also possible in this case to cope with a considerable radial offsetof the bottle relative to the shuttle. In other respects, thisembodiment can operate in the manner already described.

We claim:
 1. Apparatus for gasifying a liquid with a discrete quantityof a fluid that is supplied in liquified form, comprising means forretaining a first container of said liquified fluid and a secondcontainer of the liquid to be gasified, a discharge conduit for thepassage of the fluid into said second container, means for sealing saidcontainer while said conduit is in communication therewith, means forconnecting said conduit to said first container for the release of theliquified fluid therefrom, at least one flow path of extended surfacearea being provided within said conduit for said fluid, said at leastone flow path being formed in a material providing a heat source forsaid fluid, whereby the fluid is caused to flow in intimate contact withsaid material for heat exchange therewith to absorb from said materialthe heat required to convert the fluid to a dry gaseous state. 2.Apparatus according to claim 1 wherein said at least one flow path ofextended surface area comprises a multiplicity of small cross-sectionflow paths within said conduit.
 3. Apparatus according to claim 2wherein dividing walls within said conduit divide the internalcross-section of the conduit into a series of smaller cross-sectionpassages that are interconnected in a manner selected from the group ofparallel connection, series connection and mixed parallel/seriesconnection, to provide said multiplicity of small cross-section paths.4. Apparatus according to claim 3 wherein the conduit comprises aplurality of co-axial tubes defining coaxial flow passages andcommunication means at opposite ends of said passages direct the fluidflow in series through said flow passages.
 5. Apparatus according toclaim 2 wherein the conduit comprises at least one passage having apermeable mass occupying its cross-section, said mass providing saidmultiplicity of small cross-section paths.
 6. Apparatus according toclaim 5 in which the permeable mass in sintered.
 7. Apparatus accordingto claim 5 in which the permeable mass is retained in position by meansof one or more permeable partitions fixed transversely across theconduit.
 8. Apparatus according to claim 1 in which the conduit isinternally formed with at least one inwardly directed partition. 9.Apparatus according to claim 1 in which electrical heating means areprovided for recuperation of heat by said heat source material. 10.Apparatus according to any claim 1 wherein a non-return valve isdisposed at least at an outlet end of the conduit.
 11. Apparatusaccording to claim 1 wherein at least one outlet orifice is provided forthe dry gas exiting from said conduit, said orifice having a restrictedcross-section limiting the rate of discharge of said gas into theliquid.
 12. Apparatus according to claim 11 comprising a valve device insaid conduit for controlling the flow of gas under pressure in theconduit, said valve device comprising a closure body displaceable withina flow chamber, peripheral sealing means between said body and thechamber, resilient biasing means urging the closure body against a gasinlet port to said chamber against the gas pressure upstream of saidinlet port, said inlet port having a cross-section less than thecross-section of the chamber at said peripheral sealing means wherebyafter displacement of the valve body by the gas pressure acting againstthe resilient bias an increased pressure force is applied to the body tomaintain the inlet port open, said outlet orifice being arranged to beplaced in communication with said inlet port by said displacement of thebody for the discharge of the gas into the liquid.
 13. Apparatusaccording to claim 12 wherein an opening is provided in said chamber fortransmitting to the closure body the prevalent pressure of the liquid,said pressure acting to urge the body towards said inlet port wherebythe movement of the closure body is responsive to the pressuredifferential between the gas at the inlet port and the liquid beingcharged with gas.
 14. Apparatus for gasifying a liquid with a discretequantity of a fluid that is supplied in liquified form, comprising meansfor retaining a first container of the liquified fluid and a secondcontainer of the liquid to be gasified, a discharge conduit for thepassage of said fluid to said second container having an outletextending from said first container retaining means to project throughan opening of said second container into the liquid therein, means forsealing said opening of the second container while said conduit outletextends into the liquid in said container, at least one flow path ofextended surface area being provided within said conduit for said fluid,said at least one flow path being formed in a material providing a heatsource for said fluid, whereby the fluid is caused to flow in intimatecontact with said material for heat exchange therewith to absorb fromsaid material the heat required to convert the fluid to a dry gaseousstate, and flow restriction means being provided in said outlet tocontrol the outlet flow of dry gas into the liquid in the secondcontainer.
 15. Apparatus for discharging a fluid from a sealed bulb intoa liquid in a container, comprising:mounting means arranged to permitrelative movement of the bulb towards the container, an opening devicedisposed between the bulb and the container for opening the bulb duringsaid relative movement to permit the fluid to flow into the container togasify the liquid in the container, said opening device being providedwith sealing means for engaging an entry opening of the containerthrough which said gas is admitted, biasing means for holding saidsealing means in engagement with said opening, said biasing meanscomprising resilient means acting upon the opening device to urge itaway from the bulb, whereby the bulb is opened by movement counter tothe direction of action of said resilient means, the fluid pressure inthe container acting upon the sealing means against said biasing meanswhereby the sealing means are displaceable away from said opening by anincrease of the container pressure over a limiting value to vent excesspressure fluid from the container.
 16. Apparatus for discharging fluidfrom a sealed bulb into a liquid in a container, comprising mountingmeans arranged to permit relative movement of the bulb towards a topopening in the container, an opening device disposed between the capsuleand the container comprising means for opening the bulb during saidrelative movement to permit the fluid to flow into the container togasify the liquid in the container, the mounting means comprisingrelatively displaceable parts for receiving the container and the bulb,co-operating toothed elements on the respective parts of the mountingmeans occupying spaced peripheral portions on each said part, spacesbetween said peripheral portions of each part at least equal inperipheral extent to their co-operating peripheral portions whereby thetwo parts can be telescoped axially together with the toothed portionson each aligned with said spaces on the other, said toothed portionsbeing thereby engageable selectively at different relative axialpositions of the parts so that said engagement is effected with thebulb-receiving part in a predetermined position relative to the topopenings of containers of different heights.
 17. Apparatus according toclaim 16 wherein the mounting means part receiving the bulb comprises abulb support, guidance means in which said support is slidable in thedirection of telescoping movement of said mounting parts, and an endstop for limiting the movement of said support when the parts aretelescoped together, whereby said engagement of the co-operating partsof the mounting means is effected at relative axial positions of saidparts dependent on the axial length of a bulb inserted in the apparatus.18. Apparatus according to claim 16 wherein the toothed portions of therelatively displaceable parts have different extents in the direction ofaxial telescoping of the parts, and guide means are provided comprisingrespective guide elements on the two parts that are engaged in theinitial telescoping of the parts to limit relative rotational movementtherebetween until at least a major part of the extent of the shortertooth portion of one of the parts is axially coincident with the longertooth portions on the other of the parts.
 19. Apparatus according toclaim 16 wherein said toothed portions comprise screw-thread segments ofthe respective parts of the mounting means, whereby engagement of thetoothed portions by relative rotation of the parts also causes relativeaxial displacement of said parts for opening the bulb.
 20. Apparatusaccording to claim 16 wherein said mounting means part for receiving thebulb comprises a holder for the bulb and retaining means to support thebulb in said holder against the reaction of the gas pressure during saidcharging, a pivot attachment for said retaining means on said mountingmeans for pivotal displacement of the retaining means relative to theholder to and from a non-operative position in which it allows access tothe holder for insertion of a bulb therein, stop means determining alimiting operative position for the retaining means after the insertionof the bulb, the pivot attachment of the retaining means being offsetfrom the line of action of the gas pressure whereby said pressure actsto urge the inserted bulb against the retaining means to hold said meansin said limiting operative position.
 21. Apparatus for discharging gasunder pressure into a liquid in a container and comprising a gasthroughflow means disposed centrally with respect to annular sealingmeans for engagement with an opening of the container opening to becircumferentially surrounded thereby, said sealing means comprising aflexible sealing member for sealing contact with the container openingand means for supporting the sealing member against said opening, thesealing means having a flexural compliance to internal pressure in thecontainer that is non-uniform with respect to its circumferential extentaround the gas injection means, at least one angular portion of thecircumferential extent of the flexural sealing member being therebyprovided with a lesser resistance to flexure whereby said at least oneportion is deformable to release excess gas pressure in the containerwhile said sealing member is retained against the container openingelsewhere around said circumferential extent of the sealing means. 22.Apparatus according to claim 21 wherein the sealing means is providedwith a plurality of portions of greater compliance circumferentiallyspaced about the gas throughflow means.
 23. Apparatus according to claim21 wherein the sealing means is provided with at least two radiallyelongate portions of greater compliance disposed substantiallysymmetrically relative to the gas throughflow means.